$\"\"$ $\"\"$

The expression is $\"\"$

$\"\"$ (Distribute 7)

$\"\"$ (Multiply: $\"\"$ )

$\"\"$ (Apply commutative property of addition: $\"\"$ )

$\"\"$

$\"\"$ (Apply associative property of addition: $\"\"$

$\"\"$ (Distribute ac)

$\"\"$ (Add: $\"\"$ )

$\"\"$

The simplified expression is $\"\"$ $\"\"$ .